The person who throws out the first official pitch at San Diego’s new downtown ballpark April 8 will go down in history. Not because he’s tossing out the first pitch, but because he’s a former president of the United States. Jimmy Carter, a close friend of Padres owners John and Becky Moores, will open the Padres’ season at Petco Park. The friendship of the two men has grown steadily since John Moores became a trustee on the board of the Carter Center at Emory University in Atlanta. Former first lady Rosalynn Carter also will attend opening ceremonies.